Ni/Co-Catalyzed Homo-Coupling of Alkyl Tosylates

Cross-selective Deoxygenative Coupling of Aliphatic Alcohols: Installation of Methyl Groups including Isotopic Labels by Nickel Catalysis

Nickel-catalyzed cross-electrophile coupling reactions of two aliphatic alcohol derivatives remain a challenge. Herein, we report a nickel-catalyzed reductive methylation reaction of aliphatic mesylates with methyl tosylate. This reaction provides straightforward access to compounds bearing aliphatic methyl groups from alkyl alcohol derivatives. Isotopically labelled substrates and reagents can be employed in the reaction to provide perdeuterated and 13C-labelled products. This transformation can be achieved by employing stoichiometric Mn reductant or electrochemically. Additionally, mechanistic experiments show that alkyl iodides are key intermediates in the transformation which undergo a stereoablative reaction via radical intermediates.

Visible light-driven Giese reaction with alkyl tosylates catalysed by nucleophilic cobalt

The scope of the Giese reaction is expanded using readily available alkyl tosylates as substrates and nucleophilic cobalt(i) catalysts under visible-light irradiation. The reaction proceeds preferentially with less bulky primary alkyl tosylates. This unique reactivity enables the regio-selective Giese reaction of polyol derivatives.

We report an efficient approach for the Giese reaction with abundant alkyl tosylates as alkyl radical sources using a nucleophilic cobalt catalyst under visible-light irradiation.

Ni-Catalyzed Reductive and Merged Photocatalytic Cross-Coupling Reactions toward sp3/sp2-Functionalized Isoquinolones: Creating Diversity at C-6 and C-7 to Address Bioactive Analogues

Naturally occurring isoquinolones have gained considerable attention over the years for their bioactive properties. While the late-stage introduction of various functionalities at certain positions, namely, C-3, C-4, and C-8, has been widely documented, the straightforward introduction of challenging sp3 carbon-linked acyclic aminoalkyl or aza- and oxacyclic appendages at C-6 and C-7 remains largely underexplored. Interest in 6-substituted azacyclic analogues has recently garnered attention in connection with derivatives exhibiting anticancer activity. Reported here is the first application of the versatile and recently emerging field of Ni-catalyzed reductive cross-coupling reactions to the synthesis of 6- and 7- hetero(cyclo)alkyl-substituted isoquinolones. In a second and complementary approach, a new set of C-6- and C-7-substituted positional isomers of hetero(cyclo)alkyl appendages were obtained from the merging of photocatalytic and Ni-catalyzed coupling reactions. In both cases, 6- and 7-bromo isoquinolones served as dual-purpose reacting partners with readily available tosylates and carboxylic acids, respectively.

Nickel-Catalyzed Alkyl-Alkyl Cross-Electrophile Coupling Reaction of 1,3-Dimesylates for the Synthesis of Alkylcyclopropanes

Cross-electrophile coupling reactions of two Csp³-X bonds remain challenging. Herein we report an intramolecular nickel-catalyzed cross-electrophile coupling reaction of 1,3-diol derivatives. Notably, this transformation is utilized to synthesize a range of mono- and 1,2-disubstituted alkylcyclopropanes, including those derived from terpenes, steroids, and aldol products. Additionally, enantioenriched cyclopropanes are synthesized from the products of proline-catalyzed and Evans aldol reactions. A procedure for direct transformation of 1,3-diols to cyclopropanes is also described. Calculations and experimental data are consistent with a nickel-catalyzed mechanism that begins with stereoablative oxidative addition at the secondary center.

Reductive amidation of alkyl tosylates with isocyanates by a Ni/Co-dual catalytic system

Reductive amidation of alkyl tosylates with isocyanates using the Ni/Co-dual catalytic system is disclosed. The method proceeds efficiently under mild conditions, giving rise to the corresponding alkyl amides. Notably, the protocol can discriminate the steric environment of two alkyl tosylate moieties, enabling regioselective mono-amidation at the less-bulky site.